MiniPato is a SD short film of Patlabor that accompanies the WXIII movie. It's animated as if the characters are cardboard cut-outs on sticks and looks darn funny It's licensed and is on the R1 special edition release of WXIII. Dunno about R4.

to add to what mrgazpacho has said, they are short "explanations" of various things to do with Patlabor.

Each one is "presented" by a member of SVU2.

One is about the reason for the type of weapons the Patlabors use, and their names.
One is about how the Patlabor mecha design was arrived at (some really fun SD versions of the Patlabors in other styles such as giant/combing/transforming ones).
The last one is how Special Vechile unit 2 manages to support itself (funding etc).